The present invention relates to a monitoring and/or alarm device and process, in particular for the monitoring and protection of goods, premises or persons, comprising a central unit, at least one peripheral facility allowing the detection of an intrusion and alarm signalling means.
Security systems are generally classified into two main categories, wire-based systems and systems comprising radio link means. The latter have numerous advantages as compared with the wire-based systems and in particular they allow easy installation of the peripheral facilities of the central unit even in locations which wire-based systems have difficulty in accessing, thus allowing better monitoring coverage and thereby better protection.
However, these wireless systems also possess drawbacks related to the use of radio channels which may intentionally or unintentionally be partially occupied, completely or partially preventing the transmission of information between the peripheral facility and the central unit.
To solve this problem, Patent EP-A-0 811 959 proposes that several radio link channels be implemented, that the availability of these channels be analysed and that the information be transmitted via the available channel.
Manufacturers of alarm equipment have moreover designed systems with several frequencies or radio channels which are relatively far apart, allowing the information emanating from the peripheral facilities to be transmitted to the central unit even if one of the frequencies is jammed by an outside signal.
However, in case of simultaneous jamming of all the frequencies, the link between the peripheral facilities and the central unit is no longer ensured, thereby rendering the alarm system inoperative if the loss of link is not detected or causing the alarm to trigger if the complete loss of link is detected. In either case, the alarm system does not fulfil its main function which is to signal the presence of an intruder in a monitored zone.
The object of the invention is to provide an improvement to wireless monitoring and/or alarm systems taking account of the above drawbacks.
Accordingly, the present invention firstly proposes a monitoring and/or alarm device comprising a central unit, at least one intrusion detection peripheral facility, signalling means and radio link means allowing radio links on several redundant channels between the central unit, and at least one intrusion detection peripheral facility, via which channels this peripheral facility is able to transmit signals to this central unit which are expected by the latter.
According to the invention, the device comprises:
means for checking the capacity or availability of each of the said link channels to transmit the said expected signals,
means for counting the number of available channels and/or the number of unavailable channels,
and transmission means for transmitting to the said signalling means a control signal corresponding to the number of available channels and/or to the number of unavailable channels so as to selectively activate these signalling means as a function of the state of the said control signal.
According to the invention, the said signalling means preferably comprise means for being placed or activated according to at least two different modes of operation as a function of at least two states of the said control signal.
According to the invention, the said signalling means are preferably audible, luminous or electrical means.
According to the invention, the said means for checking the availability of each of the said link channels comprise means for measuring the noise level in each of the said channels and means for checking the presence of an expected signal originating from a peripheral facility.
According to the invention, the said transmission means preferably deliver the said control signal each time the number of available and/or unavailable channels is modified during at least one specified duration.
According to the invention, the said signalling means preferably comprise means for being placed or activated according to different modes of operation according to whether the said transmission means transmit the said control signal or a signal corresponding to an intrusion detection.
The present invention also proposes a monitoring and/or alarm process comprising a central unit, at least one intrusion detection peripheral facility, signalling means and radio link means allowing radio links on several redundant channels between the central unit and at least one intrusion detection peripheral facility, via which this facility is able to transmit signals to this central unit which are expected by the latter.
According to the invention, the process consists:
in checking the capacity or availability of each of the said link channels to transmit the said expected signals,
in counting the number of available channels and/or the number of unavailable channels,
and in transmitting to the said signalling means a control signal corresponding to the said number of available channels and/or to the said number of unavailable channels so as to selectively activate these signalling means as a function of the state of the said control signal.
According to the invention, the process preferably consists in placing or activating the said signalling means according to at least two different modes of operation as a function of at least two states of the said control signal.
According to the invention, the process preferably consists:
in measuring the noise level in each of the said channels
and in checking the presence of an expected signal originating from a peripheral facility.
According to the invention, the process preferably consists in delivering the said control signal each time the number of available and/or unavailable channels is modified during at least one specified duration.
According to the invention, the process preferably consists in placing or activating the said signalling means according to different modes of operation according to whether the said transmission means transmit the said control signal or a signal corresponding to an intrusion detection.